(1) Field of the Invention
The present invention relates to a mobile machine for leveling, lining and tamping a track switch comprising a main track and a branch track laterally adjacent the main track resting on ballast, each track consisting of two rails fastened to successive ties, which comprises a machine frame supported on undercarriages for movement along the main track in an operating direction, a track lifting and lining tool carrier frame mounting lining tools including a pair of flanged lining rollers arranged for supporting the carrier frame on the rails of the main track and for lining engagement with the main track rails, and lifting tools including a respective vertically and laterally adjustable clamping element, such as a rail-engaging hook and/or roller, arranged for clamping engagement with the main track rails, and lifting and lining power drive means connecting the carrier frame to the machine frame for vertically and laterally adjusting the carrier frame with respect to the machine frame.
(2) Description of the Prior Art
U.S. Pat. No. 4,627,360, dated Dec. 9, 1986, discloses such a machine whose track tamping, lifting and lining units are specifically designed for operation in track switch sections. The transversely displaceable track tamping units have, per track rail, two or four reciprocatory tamping tools at the field and gage sides of each rail and the tamping tools are independently adjustable in the direction of elongation of the ties. This arrangement enables tie tamping even in the most difficult areas of a switch with at least one of the tamping tools while any of the other tamping tools encountering an obstacle may be adjusted upwardly out of contact with the obstacle. To enable such a track switch, with its long ties and complex rails, to be gripped for leveling and lining, the longitudinally displaceable track lifting and lining unit comprises a strong lifting hook per rail and hydraulic drives for laterally and vertically adjusting each lifting hook. Such lifting hooks are capable of engaging the rails in the most difficult areas either by the rail head or at the rail base. Such switch tampers are very important for a proper maintenance of railroad tracks since the expensive track switch sections require proper positioning and this is assured by suitable leveling and lining reference systems which control the operation of the lifting and lining tools. However, the accuracy of the leveling operation is somewhat impeded because it involves the lifting of the very heavy switch section including the branch track laterally adjacent the main track. For this reason, a controlled leveling operation is often repeated during subsequent surfacing of the branch track during which this correct level is fixed by tamping the ties of the branch track.
U.S. Pat. No. 4,323,013, dated Apr. 6, 1982, discloses a track leveling, lining and tamping machine for use in tangent and switch track sections. The machine comprises a tool carrier frame having a central, forwardly projecting boom linked to the machine frame supported by a pair of flanged wheels on the track rails and mounting, per rail, a pair of lifting rollers and a lifting hook therebetween. Two lifting and two lining drives connect the tool carrier frame to the machine frame. The flanged wheels serve as lining tools. The lifting rollers are laterally pivotal into clamping engagement with the associated rail and each lifting hook is vertically and laterally adjustable for engaging either the rail head or rail base, and these lifting tools cooperate for lifting even very heavy track switches. In a simplified embodiment, only a single lifting roller is arranged for cooperation with the lifting hook at each rail for selectively or together engaging a field side of the associated rail. The flange of the flanged wheel serving as lining tool engages the gage side of the rail so that the same is firmly clamped between the lining tool and the lifting roller and/or hook. In most instances, this arrangement suffices for effectively leveling and lining even the most difficult track switches, and this machine has been very successful in commercial track maintenance and rehabilitation work. However, in this machine, too, the very heavy weight of the adjacent branch track disadvantageously stresses the lifting drives and tools so that the leveling accuracy is impaired. To relieve this heavy load, it has been proposed to mount lifting winches in the range of the branch track for assisting in the raising of the branch track but this requires additional operating personnel and also considerably slows the operation. The lifting winches must be dismounted and remounted again after each intermittent tie tamping cycle, which makes the work very cumbersome and slow.
U.S. Pat. No. 4,342,263, dated Aug. 3, 1982, also discloses a track leveling, lining and tamping machine with a two-part carrier frame for a track lifting and lining assembly, the upper part of the carrier frame having a central, forwardly projecting boom mounted on the machine frame for longitudinal displacement with respect thereto. A pair of flanged rollers supports the lower part of the carrier frame on the track rails. A transversely displaceable, pivotal lifting hook is mounted on the upper carrier frame part in the range of each flanged roller for clamping engagement with the associated rail. A vertical adjustment drive connects the upper carrier frame part to the lower carrier frame part for vertically adjusting the lifting hooks mounted on the upper part. Two lifting and lining drives and a longitudinal displacement drive connect the carrier frame to the machine frame. Since only a single lifting tool is provided for each rail, this machine cannot be used for lifting heavy track sections and it also is incapable of lifting track sections which have obstacles in the way of the lifting tools, such as are encountered in track switches. Obviously, the above-indicated disadvantages in handling the heavy weights of branch tracks in track switches are even more pronounced in the operation of this machine.
A similar track leveling, lining and tamping machine with a pair of flanged lining wheels cooperating with associated lifting hooks or rollers is disclosed in UK patent application No. 2,140,061, published Nov. 21, 1984. In view of the limited number of rail-engaging tools for lifting the track, the machine has the above-indicated disadvantages when working in track switches.